This invention relates to a motor assist apparatus for a vehicle, and particularly to a motor assist apparatus connected in series between the vehicle engine and the transmission and sized lengthwise so as to correspond to the spacing between adjacent cylinders of the engine to permit use of common parts from an engine with one additional cylinder.
There is known a vehicle having a motor assist apparatus for assisting driving force of an internal combustion engine which functions as a power source for the vehicle. The motor assist apparatus assists driving force of the engine according to a driving state. Such motor assist apparatus attains improvements of output and fuel efficiency of the engine, and can lower detrimental components in engine exhaust gases.
One example of such a motor assist apparatus for a vehicle is disclosed in published Japanese Patent Application Laid-Open No. 11-78555. The motor assist apparatus connects a motor generator, a flywheel and a transmission with a crankshaft in this order. A starter motor is connected with a ring gear on an outside of the flywheel, and the starter motor is mounted to an internal-combustion engine through a case of the transmission.
When adapting a usual motor assist apparatus to a vehicle, the engine, the transmission and the parts which mount the motor assist are prepared exclusively to accommodate the motor assist apparatus. As a result, this causes costs to increase due to the number of parts and facilities required.
To obviate or minimize the above inconvenience, the present invention provides a motor assist apparatus for a vehicle and having the motor for assisting driving force of an engine, which apparatus is built in a motor housing installed between a cylinder block of the vehicle engine and a case of the vehicle transmission, and which motor housing has a predefined or set length in the cylinder line direction so as to be equal to the distance between the centers of cylinders of the engine.
In a motor assist apparatus for a vehicle according to this invention, the motor housing is installed between the engine cylinder block and the transmission casing, and has a length in the cylinder line direction (i.e., the direction of the crankshaft axis) which is equal to the distance between the centers of cylinders of the engine, whereby the length of the engine with the motor assist apparatus in the cylinder line direction can be coordinated so as to be the same length as an engine having one more cylinder. For example, this motor assist apparatus can be coordinated so that the length of a 3-cylinder engine having a motor becomes the same as the length of 4-cylinder engine. By the way, in the engine to adopt this motor assist apparatus, it is possible to utilize a part of engine being one cylinder more than this engine.